amos/zbunk.f

   1       SUBROUTINE ZBUNK(ZR, ZI, FNU, KODE, MR, N, YR, YI, NZ, TOL, ELIM,
   2      * ALIM)
   3 C***BEGIN PROLOGUE  ZBUNK
   4 C***REFER TO  ZBESK,ZBESH
   5 C
   6 C     ZBUNK COMPUTES THE K BESSEL FUNCTION FOR FNU.GT.FNUL.
   7 C     ACCORDING TO THE UNIFORM ASYMPTOTIC EXPANSION FOR K(FNU,Z)
   8 C     IN ZUNK1 AND THE EXPANSION FOR H(2,FNU,Z) IN ZUNK2
   9 C
  10 C***ROUTINES CALLED  ZUNK1,ZUNK2
  11 C***END PROLOGUE  ZBUNK
  12 C     COMPLEX Y,Z
  13       DOUBLE PRECISION ALIM, AX, AY, ELIM, FNU, TOL, YI, YR, ZI, ZR
  14       INTEGER KODE, MR, N, NZ
  15       DIMENSION YR(N), YI(N)
  16       NZ = 0
  17       AX = DABS(ZR)*1.7321D0
  18       AY = DABS(ZI)
  19       IF (AY.GT.AX) GO TO 10
  20 C-----------------------------------------------------------------------
  21 C     ASYMPTOTIC EXPANSION FOR K(FNU,Z) FOR LARGE FNU APPLIED IN
  22 C     -PI/3.LE.ARG(Z).LE.PI/3
  23 C-----------------------------------------------------------------------
  24       CALL ZUNK1(ZR, ZI, FNU, KODE, MR, N, YR, YI, NZ, TOL, ELIM, ALIM)
  25       GO TO 20
  26    10 CONTINUE
  27 C-----------------------------------------------------------------------
  28 C     ASYMPTOTIC EXPANSION FOR H(2,FNU,Z*EXP(M*HPI)) FOR LARGE FNU
  29 C     APPLIED IN PI/3.LT.ABS(ARG(Z)).LE.PI/2 WHERE M=+I OR -I
  30 C     AND HPI=PI/2
  31 C-----------------------------------------------------------------------
  32       CALL ZUNK2(ZR, ZI, FNU, KODE, MR, N, YR, YI, NZ, TOL, ELIM, ALIM)
  33    20 CONTINUE
  34       RETURN
  35       END